A number of methods for making instant tea from tea concentrates are known, but no commercially successful product has been found because consumers have rejected all prior attempts. Vending machines exist which dispense tea concentrates for making instant tea. However, a problem with these machines is that the tea that is produced by them tends to have poor flavour and aroma.
While instant coffee is widely accepted as a convenient, if inferior, substitute for freshly brewed coffee, instant tea has never achieved this status. Tea concentrates, from which instant tea can be made, are available as dried powders (analogous to instant coffee) and liquids. However, the dried powder concentrates produce instant tea with very poor flavour. With instant coffee the poorer flavour compared to freshly brewed coffee has been accepted as a reasonable compromise for the benefits of speed, convenience and low cost. However, dried instant tea has never caught on because the flavour is so inferior to freshly brewed tea. The liquid tea concentrates can sometimes offer a good approximation to the aroma of freshly brewed tea. However, while the aroma from these liquid extracts can be better than that from dried powder concentrates, the flavour of the tea that is produced is still very poor.
Concentrates for instant iced teas are commercially available. However, these rely on sugar to stabilise the iced tea concentrate. Many people choose to drink hot tea without sugar, and so any tea concentrate cannot rely on the use of sugar as a stabilising agent.
Tea cream is a phenomenon that develops in strong tea as it cools, where the tea becomes cloudy and drops a deposit. In the production of commercial tea concentrates, both dried powders and liquid extracts, the tea cream is seen as a problem that must be removed as cloudiness or deposits in any final tea drink are seen as a fault. There are a number of ways that this can be dealt with, including removal by centrifugation or precipitation, heating, ultrafiltration, or by precipitating with calcium chloride or bentonite, or by a number of oxidative or enzyme catalysed reactions. One of these processes is always performed before drying tea extract to make a powdered “instant tea” and nearly always also applied to liquid tea extract.
The problem is that key elements of the tea flavour, namely the tannins which give astringency, and the caffeine which gives the refreshing stimulant effect are concentrated in the precipitate which is removed. The characteristic aroma of tea is in the liquid fraction and this is retained, but the other elements are lost. Typically such tea extracts are used in compound drinks, such as iced teas or spiced chai, where their paucity of flavour is compensated for by other added flavour elements. Liquid tea extracts that are available commercially to the consumer, such as the US brand, “Walkers”, have tea cream removed, and as a result have poor flavour. Attempts to commercialise them by direct sale to the consumer as instant tea have therefore had limited success.